Thalamic and hippocampal volume associated with memory functions in multiple sclerosis.

OBJECTIVES: Although multiple sclerosis (MS) has long been considered to primarily affect white matter, it is now recognized that cognitive deficits in MS are also related to neocortical, thalamic and hippocampal damage. However, the association between damage to these structures and memory deficits in MS is unclear. This study examines whether MS patients with cognitive impairment have a reduction of hippocampal and/or thalamic volumes compared to cognitively intact patients, and whether these volume reductions correlate with various aspects of memory function. METHODOLOGY: Volumetric MRI measures of thalamus and hippocampus of forty-one patients with MS were performed. The patients were divided in two groups depending on the presence or absence of cognitive impairment, based on their neuropsychological tests scores. RESULTS: Right hippocampal volume was found to be associated with learning, and the left thalamic volume was found to predict performance in verbal memory. Cognitively impaired patients had a tendency to have a reduced left thalamic volume compared to cognitively intact patients. CONCLUSIONS: This study does not support a direct relationship between hippocampal atrophy and verbal memory. These results add to the growing evidence of the involvement of thalamus in cognitive impairment in MS and its association with verbal memory deficits.

Prospective memory impairment in multiple sclerosis: a review.

OBJECTIVE: Multiple sclerosis (MS) is a progressive disease of the central nervous system affecting information processing speed, episodic memory, attention, and executive functions. MS patients also often report prospective memory (PM) failures that directly impact their functional autonomy, including professional and social life. The purpose of this paper was to review the literature concerning the assessment and remediation of PM deficits in MS. METHOD: The literature pertaining to PM impairment in MS was carefully reviewed using PubMed, PsyINFO, and Google Scholar, as well as cross-references from the articles published on this topic. Since PM rehabilitation in MS patients is still in its infancy, this review mainly focuses on studies that have directly assessed PM through various measures including questionnaires, standardized clinical tests, and experimental procedures. CONCLUSION: This literature review confirms the presence of PM deficits in MS patients, even in the early stages of the disease. A further need for controlled studies on PM assessment and PM interventions in patients with MS is stressed.

Prospective memory in multiple sclerosis: The impact of cue distinctiveness and executive functioning.

OBJECTIVE: Prospective memory (PM), the ability to remember to do something at the appropriate time in the future, is crucial in everyday life. One way to improve PM performance is to increase the salience of a cue announcing that it is time to act. Multiple sclerosis (MS) patients often report PM failures and there is growing evidence of PM deficits among this population. However, such deficits are poorly characterized and their relation to cognitive status remains unclear. To better understand PM deficits in MS patients, this study investigated the impact of cue salience on PM, and its relation to retrospective memory (RM) and executive deficits. METHODS: Thirty-nine (39) MS patients were compared to 18 healthy controls on a PM task modulating cue salience during an ongoing general knowledge test. RESULTS: MS patients performed worse than controls on the PM task, regardless of cue salience. MS patients' executive functions contributed significantly to the variance in PM performance, whereas age, education and RM did not. Interestingly, low- and high-executive patients' performance differed when the cue was not salient, but not when it was, suggesting that low-executive MS patients benefited more from cue salience. CONCLUSIONS: These findings add to the growing evidence of PM deficits in MS and highlight the contribution of executive functions to certain aspects of PM. In low-executive MS patients, high cue salience improves PM performance by reducing the detection threshold and need for environmental monitoring.

Role of executive functions in prospective memory in multiple sclerosis: Impact of the strength of cue-action association.

OBJECTIVES: Patients diagnosed with multiple sclerosis (MS) often report prospective memory (PM) deficits. Although PM is important for daily functioning, it is not formally assessed in clinical practice. The aim of this study was to examine the role of executive functions in MS patients' PM revealed by the effect of strength of cue-action association on PM performance. METHOD: Thirty-nine MS patients were compared to 18 healthy controls matched for age, gender, and education on a PM task modulating the strength of association between the cue and the intended action. RESULTS: Deficits in MS patients affecting both prospective and retrospective components of PM were confirmed using 2 × 2 × 2 mixed analyses of variance (ANOVAs). Among patients, multiple regression analyses revealed that the impairment was modulated by the efficiency of executive functions, whereas retrospective memory seemed to have little impact on PM performance, contrary to expectation. More specifically, results of 2 × 2 × 2 mixed-model analyses of covariance (ANCOVAs) showed that low-executive patients had more difficulty detecting and, especially, retrieving the appropriate action when the cue and the action were unrelated, whereas high-executive patients' performance seemed to be virtually unaffected by the cue-action association. CONCLUSIONS: Using an objective measure, these findings confirm the presence of PM deficits in MS. They also suggest that such deficits depend on executive functioning and can be reduced when automatic PM processes are engaged through semantic cue-action association. They underscore the importance of assessing PM in clinical settings through a cognitive evaluation and offer an interesting avenue for rehabilitation.

Different effects of anterior temporal lobectomy and selective amygdalohippocampectomy on verbal memory performance of patients with epilepsy.

The advantage of selective amygdalohippocampectomy (SAH) over anterior temporal lobectomy (ATL) for the treatment of temporal lobe epilepsy (TLE) remains controversial. Because ATL is more extensive and involves the lateral and medial parts of the temporal lobe, it may be predicted that its impact on memory is more important than SAH, which involves resection of medial temporal structures only. However, several studies do not support this assumption. Possible explanations include task-specific factors such as the extent of semantic and syntactic information to be memorized and failure to control for main confounders. We compared preoperative vs. postoperative memory performance in 13 patients with SAH with 26 patients who underwent ATL matched on side of surgery, IQ, age at seizure onset, and age at surgery. Memory function was assessed using the Logical Memory subtest from the Wechsler Memory Scales - 3rd edition (LM-WMS), the Rey Auditory Verbal Learning Test (RAVLT), the Digit Span subtest from the Wechsler Adult Intelligence Scale, and the Rey-Osterrieth Complex Figure Test. Repeated measures analyses of variance revealed opposite effects of SAH and ATL on the two verbal learning memory tests. On the immediate recall trial of the LM-WMS, performance deteriorated after ATL in comparison with that after SAH. By contrast, on the delayed recognition trial of the RAVLT, performance deteriorated after SAH compared with that after ATL. However, additional analyses revealed that the latter finding was only observed when surgery was conducted in the right hemisphere. No interaction effects were found on other memory outcomes. The results are congruent with the view that tasks involving rich semantic content and syntactical structure are more sensitive to the effects of lateral temporal cortex resection as compared with mesiotemporal resection. The findings highlight the importance of task selection in the assessment of memory in patients undergoing TLE surgery.

Value of the MoCA test as a screening instrument in multiple sclerosis.

OBJECTIVE: Since a large proportion of multiple sclerosis (MS) patients exhibit cognitive deficits, it is important to have reliable and cost-effective screening measures that can be used to follow patients effectively. the objective of this study was to evaluate the clinical value of the Montreal Cognitive Assessment (MoCA) test in detecting cognitive deficits in MS patients. METHODS: Forty-one (70.1% women, mean age 44.51 ±7.43) mildly impaired (EDSS: 2.26 ±1.87) MS patients were recruited for this study. In addition to the MoCA, they were administered the MSNQ-P (patient version) and the MSNQ-I (informant version), the bDI-FS and a comprehensive neuropsychological test battery. RESULTS: there were significant correlations between the MoCA test and the three factors derived from the neuropsychological evaluation (Executive/speed of processing, Learning, Delayed recall). the MoCA test was correlated with the MSNQ-I but only marginally with the MSNQ-P. In addition, there was no significant correlation between the MSNQ-P and the neuropsychological factors, whereas significant correlations were found between two of those factors (Learning and Delayed recall) and the MSNQ-I, suggesting that the informant version is more reliable than the patient version for the presence of cognitive deficits. CONCLUSION: the results obtained in the present study support the value of the MoCA test as a screening tool for the presence of cognitive dysfunction in MS patients, even in patients with mild functional disability (EDSS).

Construction of graphic symbol utterances by children, teenagers, and adults: the effect of structure and task demands.

PURPOSE: This study investigated the impact of syntactic complexity and task demands on construction of utterances using picture communication symbols by participants from 3 age groups with no communication disorders. METHOD: Participants were 30 children (7;0 [years;months] to 8;11), 30 teenagers (12;0 to 13;11), and 30 adults (18 years and above). All participants constructed graphic symbol utterances to describe photographs presented with spoken French stimuli. Stimuli included simple and complex (object relative and subject relative) utterances describing the photographs, which were presented either 1 at a time (neutral condition) or in an array of 4 (contrast condition). RESULTS: Simple utterances lead to more uniform response patterns than complex utterances. Among complex utterances, subject relative sentences appeared more difficult to convey. Increasing the need for message clarity (i.e., contrast condition) elicited changes in the production of graphic symbol sequences for complex propositions. The effects of syntactic complexity and task demands were more pronounced for children. CONCLUSION: Graphic symbol utterance construction appears to involve more than simply transferring spoken language skills. One possible explanation is that this type of task requires higher levels of metalinguistic ability. Clinical implications and directions for further research are discussed.